1. Field of the Invention
The present invention relates to a communication monitoring method of monitoring network communication, a communication monitoring system, a management system, and an external device.
2. Description of the Related Art
To check end-to-end network communication, the network communication is monitored by use of a probe connected to an edge router at the border of the network.
FIG. 1 illustrates a system configuration of one example of an existing communication monitoring system. In this drawing, edge routers 2a to 2f in a network 1 are connected to probes 3a to 3f, respectively. The edge router 2a is connected to an operation system (OPS) 4 managing the network 1.
The probe 3a connected to the edge router 2a checks communication with all of the other probes 3b to 3f through the network 1. As a result of the checking, when detecting a communication break, the probe 3a notifies the operation system 4 of the communication break. The other probes 3b to 3f check communication in a similar way. When a communication break is detected, the communication break is notified to the operation system 4.
One example of a mechanism for consolidating the management of monitoring results is disclosed in Japanese Unexamined Patent Application Publication No. 2001-282761. With this mechanism, if a health check server and each terminal of a distributed system cannot communicate with one another and the management of health check results is unable to be consolidated, the health check server is changed.
In the illustrated existing communication monitoring system, for example, if there is a failure in the path between the edge routers 2c and 2a being a notification path from the probe 3c to the operation system 4 and a communication break occurs between the probes 3c and 3a, the probe 3c cannot send a notification of confirmation of communication to the operation system 4.
In addition, because a notification to the operation system 4 employs a user datagram protocol (UDP) packet, the notification may be discarded and lost within the network 1. One approach to addressing this is to employ a transmission control protocol (TCP) packet. With this approach, however, a retry repeatedly occurs when a communication break is present, and this results in a significant load on the network 1.
There are other possible approaches to addressing the above problems. For example, a network different from the network 1 may be constructed to be used for a communication path to the operation system 4, or alternatively, the network 1 may be used in an in-band manner by employing a network routing technique.
However, the construction of a different network significantly increases the cost of equipment, and this causes poor economics. With the in-band approach employing a routing technique, because an edge router performs routing for a notification as a result of checking communication, the edge router has an increased load. Additionally, to provide a notification as a result of checking communication in an in-band manner, a high-performance edge router capable of processing an increased amount of processing is necessary, and this leads to poor economics. Furthermore, if the edge router has a silent failure, such as one undetectable by the edge router, routing does not work and the operation system 4 cannot be notified of the communication break.
The present invention is made to solve the above problems. It is an object of a communication monitoring system disclosed herein to provide a method and system of notifying a communication break in an in-band manner without causing poor economics.